As is well known, optical discs can retain data for a very long time when compared with the hard disc drive and the solid state drive (SSD). Consequently, the seldom-read cold data are usually stored in the optical discs.
FIG. 1 is a schematic functional block diagram illustrating the architecture of an optical disc drive system. As shown in FIG. 1, the optical disc drive system comprises an optical disc drive 10 and a host 12. The optical disc drive 10 is connected with the host 12 through an external bus 20. The optical disc drive 10 comprises a control circuit 101 and a buffer 113. For example, the external bus 20 is a SATA bus, and the buffer 113 is a dynamic random access memory (DRAM).
When the host 12 intends to store a write data into an optical disc 115, the host 12 issues a write command and a write data to the optical disc drive 10. The write data is temporarily stored in the buffer 113 by the control circuit 101. Then, the control circuit 101 controls an optical pickup head to emit a laser beam to burn the write data to the corresponding track of the optical disc 115.
FIGS. 2A-2D schematically illustrate a writing process for the optical disc drive system. For example, the writing process is a sequential writing process.
After the previous writing operation of the optical disc 115 is completed, a next write address (NWA) is recorded in a lead-in area of the optical disc 115. When the optical disc drive 10 receives the write data and the write command from the host 12 again, the optical disc drive 10 reads the previously-recorded next write address (NWA) from the lead-in area of the optical disc 115. In addition, the optical disc drive 10 burns the write data to the tracks of the optical disc 115 from the next write address (NWA).
As shown in FIG. 2A, the next write address NWAn−1 has been recorded in the optical disc 115. For example, the host 12 intends to burn the write data to the optical disc 115. The write data contains a first data file (Data file 1) and a second data file (Data file 2).
Firstly, the host 12 issues the write command and starts to transmit the write data to the buffer 113. During the process of transmitting the write data, the write data is divided into plural data blocks by the host 12. The data blocks are sequentially transmitted to the optical disc drive 10 and temporarily stored in the buffer 113. For example, the data amount of each data block is 64K bytes.
As shown in FIGS. 2A, 2B, 2C and 2D, the received data is temporarily stored in the buffer 113.
Please refer to FIG. 2A. After a sufficient amount of write data has been accumulated in the buffer 113, the control circuit 101 starts the writing operation. In addition, the control circuit 101 controls the optical pickup head to burn the write data to the corresponding track of the optical disc 115 from the next write address NWAn−1.
Please refer to FIG. 2B. While the optical pickup head burns the write data to the corresponding track of the optical disc 115, the write data is continued to transmit from the host 12 to the buffer 113.
Please refer to FIG. 2C. The entire of the write data has been transmitted from the host 12 to the buffer 113. Meanwhile, the optical pickup head still burns the write data to the corresponding track of the optical disc 115. That is, the entire of the write data has not been completely burnt to the corresponding track of the optical disc 115.
Please refer to FIG. 2D. After the first data file (Data file 1) and the second data file (Data file 2) of the write data are burnt to the corresponding track of the optical disc 115, the writing operation is completed. That is, the entire of the write data has been completely burnt to the optical disc 115. Meanwhile, the next address of the final burning address of the track of the optical disc 115 is the new next write address NWAn. In addition, the new next write address NWAn is recorded in the lead-in area of the optical disc 115.
FIG. 3 schematically illustrates the relationship between the optical disc and the buffer when an optical disc write failure occurs. While the control circuit 101 starts to perform the writing operation and control the optical pickup head to burn the write data to the corresponding track of the optical disc 115 from the next write address NWAn−1, the write data is continued to transmit from the host 12 to the buffer 113.
While the optical pickup head burns the write data to the position 300 of the track of the optical disc 115 and the optical disc write failure occurs, the optical disc drive 10 stops burning the write data and also stops operation. Meanwhile, the optical disc drive 10 responds a write fail message to the host 12.
Since the optical disc drive 10 is not successfully burn the entire of the write data to the optical disc 115 and the optical disc drive 10 stops operation, the control circuit 101 cannot update the new next write address NWAn in the lead-in area of the optical disc 115. Without the new next write address NWAn, the optical disc drive 10 cannot continue to perform any writing operation on that optical disc 115.
Nowadays, the storage capacity of the optical disc is gradually increased. The storage capacity of the single-layer Blu-ray disc reaches 25 G bytes. The storage capacity of the dual-layer Blu-ray disc reaches 50 G bytes. The storage capacity of the triple-layer Blu-ray disc exceeds 100 G bytes.
As mentioned above, if the optical disc write failure occurs while the optical disc drive performs the writing operation on an optical disc, the optical disc drive cannot continue to perform any writing operation on that optical disc. Since the storage capacity of the Blu-ray disc is very huge, once the optical disc write failure occurs and the residual storage space on that Blu-ray disc is no longer available, a lot of storage space is wasted.